The clinical utility of the foveal electroretinogram: a review.

The historical development of the foveal electroretinogram is reviewed. The factors required to obtain a local cone electroretinogram with a small focal source of illumination against a lighted background are discussed. From these considerations and various studies of macular degeneration, the optimal size of the foveal source is found to be 5 degrees diameter or less. Applications of the foveal electroretinogram in various diseases are summarized. The foveal electroretinogram is abnormal with reduced acuity in age-related macular degeneration, juvenile macular degeneration (Stargardt's disease), retinitis pigmentosa, and diabetic retinopathy. Normal foveal electroretinograms are found in optic atrophy, amblyopia, and optic neuritis. Foveal electroretinograms are normal or abnormal in Best's disease, central serous retinopathy, and several other diseases discussed.